Last change
on this file since 377 was 352, checked in by coas-nagasima, 6 years ago |
arm向けASP3版ECNLを追加
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Property svn:eol-style
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native
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Property svn:mime-type
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File size:
837 bytes
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[352] | 1 | #include "libm.h"
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| 2 |
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| 3 | /* sinh(x) = (exp(x) - 1/exp(x))/2
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| 4 | * = (exp(x)-1 + (exp(x)-1)/exp(x))/2
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| 5 | * = x + x^3/6 + o(x^5)
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| 6 | */
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| 7 | double sinh(double x)
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| 8 | {
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| 9 | union {double f; uint64_t i;} u = {.f = x};
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| 10 | uint32_t w;
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| 11 | double t, h, absx;
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| 12 |
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| 13 | h = 0.5;
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| 14 | if (u.i >> 63)
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| 15 | h = -h;
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| 16 | /* |x| */
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| 17 | u.i &= (uint64_t)-1/2;
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| 18 | absx = u.f;
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| 19 | w = u.i >> 32;
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| 20 |
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| 21 | /* |x| < log(DBL_MAX) */
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| 22 | if (w < 0x40862e42) {
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| 23 | t = expm1(absx);
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| 24 | if (w < 0x3ff00000) {
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| 25 | if (w < 0x3ff00000 - (26<<20))
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| 26 | /* note: inexact and underflow are raised by expm1 */
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| 27 | /* note: this branch avoids spurious underflow */
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| 28 | return x;
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| 29 | return h*(2*t - t*t/(t+1));
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| 30 | }
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| 31 | /* note: |x|>log(0x1p26)+eps could be just h*exp(x) */
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| 32 | return h*(t + t/(t+1));
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| 33 | }
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| 34 |
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| 35 | /* |x| > log(DBL_MAX) or nan */
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| 36 | /* note: the result is stored to handle overflow */
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| 37 | t = 2*h*__expo2(absx);
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| 38 | return t;
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| 39 | }
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